Manufacture of reducing alkaline melts



E. BERGVE.

MANUFACTURE OF REDUCING ALKALINE MELTS.

APPLICATION FILED MAR. 10. 1919,

1,354,451. PatentedSept. 28,1920.

UNITED STATES PATENT OFFICE.

EINAR BERG-VB, OF CHRISTIANIA, NORWAY, ASSIGNOR TO NORSK HYDRO-ELEKTRISK KVAELSTOFAKTIESELSKAB, OF CHRISTIANIA, NORWAY.

MANUFACTURE OF REDUCING ALKALINE MELTS.

Application filed March 10, 1919.

To all whom it may concern:

Be it known that I, EINAR BERGVE, a subject of the King of Norway, of Christiania, Norway, have invented certain new and useful Improvements in the Manufacture of Reducing Alkaline Melts; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it a pertains to make and use the same.

Tliis invention relates to the manufacture of alkaline reducing melts and has for its object to produce a reducing melt having a low melting point as well as an improved process for the production of such melts.

In organic syntheses particularly for the manufacture of dyes, such as indigo, alkaline melting operations are frequently comprised in the processes, the said melting operation being effected by the use of hydroxid of potassium, to which sodium metal or sodium amid has been added. The action of the said metallic aluminium or the aluminium amid, as known, is due to the fact that the water formed is immediately removed.

In order to attain the greatest possible output it is of importance that the temperature of the melt be as low as possible.

The present invention is based upon the observation that it is possible to lower the temperature of the alkaline reducing melt below the temperature hitherto employed in connection with the use of sodium amid and at the same time to increase the reducing action. This is made possible by dissolving metallic sodium or potassium in alkali metal hydroxid preferably in an equimolecular mixture of the hydroxids of sodium and potassium. I

Preferably the metal dissolved in the,h v-

droxid consists of about one sodium to two potassium N aK lg I have found t at when an equimolecular mixture of sodiumand potassium hydroxids is electrolyzed with a sufiiciently low current density at the cathode the separated metal immediately enters into solution again and a homogeneous melt is produced which ':ontains the alkali metals in the proportion above stated (NaK Example I.

A melt consisting of per cent sodium hydroxid' and per cent. potassium h'y- Specification of Letters Patent.

solved in the melt.

a cathode K and Patented Sept. 28, 1920. Serial No. 281,753.

droxid (melting point 167) is electrolyzed at a temperature of 175 C. by the use of a bath tension of about 3 volts and with a cathodic current density of about 100 amp. per square centimeter.

he potassium-sodium alloy is then separated in the proportion of 77 per cent. potassium and 23 per cent. sodium. Immediately on being separated the metals are dis- After having attained the desired percentage of the alkali metals the melt is cooled to a temperature suitable for the reaction in which it is to be employed, provided the melt is made at the laboratory where it is to be used. If the melt is to be transported, the cooling is carried to the point of solidification.

If it is desired to produce a reducing melt containing more sodium than potassium this may be attained as follows:

Example I I A melt consisting of 70 per cent. sodium hydroxid and 30 per cent. potassium hydroxid (meltin point 240 C.) is electrolyzed at 246 by the use of a tension of about 3 volts and with the same cathode current density as in Example I. The alkali metals are then separated in the proportions of 71 per cent. of sodium and 29 per cent. of potassium.

In order to obtain the best possible proportion of the solution of alkali metals in the melt it is of advanta e to use a low cathodic current density {I to 0.01 amperes per square centimeter) and a high anodic current density (up to 50 amperes per square centimeter). By working with these melts which have a comparatively low melting point a good current output is attained. The current output may be further increased by working in vacuum, in an indifferent atmosphere or by protecting the melt with oils of a high boiling point.

In the drawing I haveshown the electrolysis carried out in an iron vessel B, constructed as illustrated. The vessel contains an anode A insulated from the vessel, and the vessel is provided with a gas-tight cover C. The melt is heated by the-internal current and the oxygen evolved escapes by one or both of the pipes P and R.

To further reduce the part1al pressure of the oxygen in the space between the sun face of the melt and the cover'C, this space may be exhausted, or an indifierent gas may be supplied through pipe P.

I claim:

1. Amelt for use with organic substances having a low melting point, comprising an alkali hydroxid in which is dissolved metallic sodium and metallic potassium.

2. A melt for use with organic substances having a low melting point, comprising an alkali hydroxid in which is dissolved metallic sodium and metallic potassium in the proportion of one molecule of sodium to two molecules of potassium.

3. A melt of mlxed alkali metal hydroxid containing metallic sodium and metallic potassium.

4. The method of producing an alkaline melt containing dissolved alkali metal for chemical reductions and syntheses, which comprises electrolyzing an alkali metal hydroxid melt.

5. The method of producing an alkaline melt containing dissolved alkali metal for chemical reductions and syntheses, which comprises electrolyzing a melt containing an equi-molecular mixture of sodium hydroxid and potassium hydroxid.

6. The method of producing an alkaline melt containing dissolved alkali metal for chemical reductions and syntheses, which comprises electrolyzing a melt containing an equi-molecular mixture of sodium hydroxid and potassium hydroxid out of contact with the air.

7 The method of producing an alkaline melt containing dissolved alkali metal for chemical reactions and syntheses, which comprises electrolyzing a metal of alkali metal hydroxid with a high anode current densi tiy and a low cathode current density.

8. he method of producing an alkaline melt containing dissolved alkali metal for chemical reductions and syntheses, which comprises electrolyzing a melt containing alkali metal hydroxid with an anode current density of from twenty to fifty amperes per square centimeter and a cathode current densit below one ampere per square centimeter.

n testimony that I claim the foregoing as my invention, I'have signed my name in presence of two subscribin witnesses.

EIN BERGVE. Witnesses:

MAGNES Braces, NANCY AELAKSEN. 

